1. Field of the Invention
This invention relates to ski devices and especially to ski devices having means for self-propulsion.
2. Discussion of Related Art
My prior U.S. Pat. Nos. 3,325,179 and 4,193,609, and my allowed U.S. patent application Ser. No. 951,443, which are all incorporated herein by reference thereto, disclose ski devices having pivoted seats mounted thereon for use on snow and other appropriate surfaces. My allowed application shows the basic ski and seat structure with various propulsion devices attached thereto. These propulsion devices include jet engines and various propeller driven arrangements for pushing the structure along the support surface. I have discovered that these types of propulsion arrangements, while useful, may possibly pose hazards that can injure the unwary. Consequently, I have developed a new propulsion system utilizing ground-engaging treads which are inherently less dangerous.
Various forms of tread propelled snow vehicles have been suggested in the past. For instance, U.S. Pat. No. 4,175,627 issued Nov. 27, 1979 to Husted shows a propulsion system for a snow going device comprising a roller chain carrying a plurality of cleats. The roller chain is powered by a small engine. The snow going device itself includes a steerable front ski and a fixed rear ski, to the rear of which the engine and roller chain are mounted. In the Husted device, propulsion is dependent upon one single tread which is completely isolated to the rear of the skis. This configuration can conceivably result in forcing a "bogging" or "mushing" effect upon the front of the device.
U.S. Pat. No. 4,162,008 issued July 24, 1979 to Best et al shows a powered snow ski with a forward steering mechanism having a depending rudder controlled by an upstanding handle bar. The rearward portion of the ski carries a motor mechanically linked to the drive roll of a belt drive depending through an opening in the rearward portion of the ski to contact an underlying supportive snow surface. The short drive belt unit of Best would appear to have a well drilling effect through a hole or door in the middle of what should be an uninterrupted ski gliding surface.
U.S. Pat. No. 2,706,528 issued Apr. 19, 1955 to Kallieo shows a snow going device having a single runner 10 containing an engine mounted on the back thereof. A drum or chain with cleats is mounted to the rear of the ski and is driven by the engine to power the ski. As with the Husted device, the disposition of the driving structure to the rear of the ski results in poor performance.
Other patents of which I am aware and which may be of interest are U.S. Pat. Nos. 2,378,111 to Tucker et al; 2,867,991 to Brandli; and 3,809,173 to McLeod.